JP1998-266978 discloses a vane pump including a rotor linked to a driving shaft, a plurality of vanes that are provided so as to be capable of reciprocating in the radial direction relative to the rotor, a cam ring that has an inner circumferential surface on which tip ends of the vanes slide by rotation of the rotor, and a pump body that has an accommodating concave portion for accommodating the cam ring.
With such a vane pump, as the rotor is rotated, the plurality of vanes are reciprocated to expand/contract pump chambers, working oil is sucked from a suction port into the pump chambers in a suction region where the pump chambers are expanded, and the working fluid is discharged from the pump chambers through a discharge port in a discharge region where the pump chambers are contracted.